Exoplanet demographics provide crucial constraints on planet formation and evolution, but their reliability depends on precise and complete measurements. I begin by presenting the results from our targeted ground-based photometric follow-up using Indian telescopes, where improved photometry and advanced denoising sharpen key demographic parameters, such as planet size and mass, showing how precise measurements directly strengthen population analyses. I then turn to small planets, where the Kepler mission remains a crucial source of knowledge. On the one hand, I focus on reprocessing Kepler’s pixel-level data with improved completeness and rigorous vetting of low-signal-to-noise detections to refine occurrence rates, including constraints on 'eta-Earth'—the frequency of Earth-sized planets in the habitable zones of Sun-like stars in our neighbourhood. These results are essential for the design of upcoming missions like the Habitable Worlds Observatory (HWO). Conversely, I explore the enigmatic worlds of super-Earths and sub-Neptunes, bridging terrestrial and Neptune-sized planets. By combining demographic trends from Kepler, the Transiting Exoplanet Survey Satellite (TESS), and ground-based radial velocity observations with formation and interior structure models, I investigate evolutionary pathways and constrain likely compositions. Together, this work provides a step toward a broader understanding of how planetary systems, including our own, formed, and how rare or common Earth-like planets may be.